I have a Rental Insurance Excess cover on the Credit Card I have. Will this give me complete coverage on any theft or any damage (windscreens, scratches etc) for which you have a €1,250 excess.
Only your credit card company would know. You would need to ask them for an opinion but you do have the option to take extra insurance when you arrive at the desk.
What is the cross border fee from portugal to spain?
Zero normally, but you can check here:-
To view the CROSS BORDER or FERRY terms and conditions. At STEP2 of our 3 step online booking process, alongside the car photo of your choice, there is a link entitled “IMPORTANT INFORMATION”. Clicking on this link will open an additional smaller window, with the terms and conditions appertaining to that particular car/supplier. Choose then the CAR tab and look under TRAVEL RESTRICTIONS
Try a few different suppliers as each supplier/vehicle type may have a different cross border rule.